X-ray or gamma ray systems or devices – Source support – Source cooling
Reexamination Certificate
1999-09-16
2001-04-10
Church, Craig E. (Department: 2882)
X-ray or gamma ray systems or devices
Source support
Source cooling
Reexamination Certificate
active
06213639
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an x-ray radiator of the rotary-bulb type having a vacuum enclosure which rotates within the radiator housing during the operation of the x-ray radiator, the radiator housing, being filled with a liquid cooling medium.
2. Description of the Prior Art
In x-ray radiators such as this, oil pumps and external coolers are sometimes forgone for reasons of cost. This means that in x-ray radiators of this type the high heat energy which is created in the x-ray conversion must be stored in the anode, and the stored heat is then conveyed to the liquid cooling medium, from which it can be released into the environment exclusively by means of convection. In turn, this means that x-ray radiators of this type can only by designed for an average power of a few 100 Watts. Besides this power limitation, a further disadvantage is that the overall cooling medium volume (generally insulating oil) of the x-ray radiator is not heated uniformly by the heat arising locally in the vicinity of the anode, and so heat is not uniformly converted through the surface of the x-ray radiator, which means that the x-ray radiator cannot be operated at a continuous power which would be optimal for the volume. Finally, in x-ray radiators of this type the danger exists that parts of the housing in the region of the anode may exceed the allowable temperature limits.
If it is desired to increase the power of x-ray radiators without external coolers, a forced-air cooling can be introduced, however, this does not solve the problem of uneven heat discharge by the tube. Besides a limited possibility to increase power, the cost reduction resulting from the avoidance of the external cooler, which is desirable, is not achieved with such a forced-air cooling, or only to a certain extent.
SUMMARY OF THE INVENTION
An object of the present invention is to provide an x-ray radiator of the type described above wherein it is possible to increase the power without external coolers or cooling medium pumps, while at the sane time the danger of thermal overloads of individual regions of the x-ray radiator is at least diminished.
This object is inventively achieved in an x-ray radiator having a cooling medium conducting body arranged between the vacuum enclosure and the radiator housing, spaced a distance from both, which body effects a flow of cooling medium along the vacuum enclosure in an inner gap located between the cooling medium conducting body and the vacuum enclosure, and a return flowing of the cooling medium along the radiator housing in an outer gap located between the body and the radiator housing. The transport of the cooling medium through the inner and outer gaps is effected by means of the rotation of the vacuum enclosure.
On the basis of the inventive construction, the cooling medium flows along the vacuum enclosure, cooling the anode, in particular, so as to avoid temperature peaks (hot spots) in the region of the anode, which were unavoidable in conventional radiator without circulating the cooling medium by means of a pump. After the heat absorption by the vacuum enclosure, the oil flows in the outer gap at the inner wall of the radiator housing and is thereby cooled. The flow against practically the entire inner wall of the radiator housing produces an appreciably better heat dissipation than was the case in conventional x-ray radiators without circulation of the cooling medium by means of a pump, in which the cooling medium is intensely heated in an uneven manner and, for lack of a forced-air circulation, does not even exploit the entire cooling surface of the radiator housing.
In the invention, the fact that an uneven pressure distribution develops in the interior of the radiator housing due to the rotation of the vacuum enclosure is exploited for the purpose of circulating the cooling medium, so that, after it has flowed along the vacuum enclosure through the inner gap and has absorbed heat therefrom, the cooling medium flows through the outer gap and here releases the absorbed heat to the radiator housing, and thus into the environment, before being transported again into the inner gap, now cooled. As long as the unevenness of the pressure distribution in the radiator housing suffices for transporting the cooling medium without special measures being taken, those skilled in the art can, without undue experimentation, influence the unevenness of the pressure distribution by a corresponding shaping of the cooling medium conducting body and the vacuum enclosure, as well as by a suitable dimensioning of the width of the inner and outer gaps, so that the pressure difference between regions with low pressure and regions with high pressure suffices for purposes of circulating the cooling medium.
A particularly intensive circulation of the cooling medium is achieved in an embodiment wherein the outer gap is connected by connecting lines, which are implemented in the cooling medium conducting body, to inlets and outlets of the inner gap, which are arranged at points of the inner gap at which there is a low pressure, or a high pressure, in the cooling medium consequent to the rotation of the vacuum enclosure.
For a particularly effective circulation of the cooling medium, in a preferred embodiment the vacuum enclosure rotates around an rotational axle, and the cooling medium conducting body has faces which extend transversely to the rotational axle, and inlets and outlets for the cooling medium respectively empty into a section of the outer gap adjacent a face of the cooling medium conducting body, in the vicinity of the rotational axle. Since the inlets and outlets empty into the sections of the outer gap that neighbor the faces, in the vicinity of the rotational axle, the cooling medium located in the outer gap flows against practically the entire wall of the radiator housing, so that nearly the entire wall of the radiator housing contributes to heat dissipation.
In a further embodiment of the invention, the cooling medium conducting body is an essentially cylindrical metal or plastic injection-molded part, which is preferably divided along a longitudinal center plane. It is advantageous particularly in the embodiment having a plastic injection-molded part, to embed lead shielding shells in the cooling medium conducting body.
REFERENCES:
patent: 5703926 (1997-12-01), Bischof
patent: 5883936 (1999-03-01), Hell et al.
patent: 6084942 (2000-07-01), Hell
Hell Erich
Mattern Detlef
Ohrndorf Thomas
Schardt Peter
Church Craig E.
Schiff & Hardin & Waite
Siemens Aktiengesellschaft
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